Vibrational Lifetime of Interstitial Oxygen in Crystalline Silicon

The lifetime of the antisymmetric stretch mode of interstitial oxygen in crystalline Si is measured directly by time-resolved, transient bleaching spectroscopy to be T1 = 229 ± 16 ps at 10 K. The temperature dependence of the lifetime shows that the stretch mode decays into eight vibrational modes of 142 ± 20 cm. The low-temperature width of the FTIR (IR) absorption line due to the stretch mode is 20 times broader than its natural width derived from the lifetime. This homogeneous broadening arises from phase relaxation induced by the coupling between the stretch mode and low-frequency bending modes.